This linguistic study centers around the word adelphos, which is Greek for brother. The following memo was emailed to me. Please read it; my response follows.

I wanted to ask you about Jesus' brothers. I was recently challenged by a Catholic that the Bible never specifically says (there is no proof) Mary had other children than Jesus. When I asked him about the numerous passages that refer to his brothers, he told me to look to the Greek. Apparently (according to http://www.blueletterbible.com) the same word for brother, adelphos {a-del-fos'}, could mean a brother, or a close relative. Here are all the definitions I got:

(1) a brother, whether born of the same two parents or only of the same father or mother;
(2) having the same national ancestor, belonging to the same people, or countryman;
(3) any fellow or man;
(4) a fellow believer, united to another by the bond of affection;
(5) an associate in employment or office;
(6) brethren in Christ

(1) and (2) are the ones that need to be dealt with. Personally, I see these definitions as supporting his view.—Robert Borgersen (Winnipeg)

I would say that these possible meanings of adelphos are all correct. Of course, a word cannot have all possible meanings simultaneously; each word as a semantic range.

Context determines the meaning, much more one's preference of dictionary definition. In the case of Jesus' family, the logical inference from Matthew 1:25 is that Joseph and Mary had normal sexual relations after Jesus was born. The seven or more siblings indicated in Matthew 12 and 23 vindicate this view. We ought to embrace the simplest view, provided there is no biblical reason to reject it.

In the case of the Catholic position that Mary remained a virgin in perpetuity, the meanings of adelphos actually support that position no more than they do the view that his "brothers" were his fellow craftsmen in the family business, as in definition (5). The semantic range in this case will need to be restricted, by context, logic, and cross-checking with other scriptures which delimit the possibilities. Once that is done, frankly speaking, the Roman position is untenable.

Let me illustrate the point before I let you go. Someone says, "She's blue." What does this mean?

(1) Reflecting light at a certain wavelength in the electromagnetic spectrum (such as the villain in the film "Big Fat Liar," whose skin had been dyed).
(2) Oxygen deprived (and therefore the blood being a different color).
(3) Sad, depressed.
(4) Noble (as in "blue blood").
(5) Barely cooked; rarer than rare (as in a blue steak).

Even though (1) is the most common sense of the word in the English language, when said of a person the word "blue" could mean (1), (2), (3) or (4). Sense (5) would be unintelligible, apart from a macabre context of cannibalism, so we will let this one go. In all likelihood, (3) is what "blue" means, although in special circumstances (1), (2) and (4) might also make sense. Once again, to insist that (1) is the true meaning of "blue" in the sentence "She's blue" may be reasonable, but in the absence of certain evidence it is almost certainly unreasonable.

So it is with the Greek word for brother. While adelphos might mean a number of things, it cannot mean all of them at once; context and careful study determine the precise meaning. (Unless, of course, Matthew was trying to be vague or ambivalent, which no one I have read holds to be the case.) The burden of proof is on the one pleading the exception.

Adelphos, the normal Greek word for one's physical brother, is the strongest contender, despite theologies which beg to differ. Were it not for the view of sexuality that was emerging in the second century AD, it is doubtful anyone would have come up with the Catholic or Orthodox interpretation of adelphos as cousin, or stepbrother. (Besides, there is a perfectly good Greek word for cousin; it is anepsios, as in Colossians 4:10.)

Further, these brothers are often found in Mary. Why would Jesus's cousins accompany her? One more fact tells against the traditional Catholic interpretation. Psalm 69, a Messianic psalm, speaks of the rejection by Christ of his brothers (v.8)—not cousins.

For more linguistic insights, search the website. Keyword: "linguistic."